The present invention relates to a TDC (top dead center) position detector of an engine.
In order to effectively operate a piston engine, the spark and fuel injection timing thereof must be set at the optimum piston position. The optimum piston position is usually determined based on the TDC position of the piston. Therefore, the TDC position must be accurately detected.
Conventionally, the TDC position has been detected by measuring the rotating angle of a crankshaft or the like connected to the piston. However, this detecting method has a problem that the undesirable unfitness occurring between the crankshaft and the connecting rod or between the connecting rod and the piston pin results in errors in detection.
Under the above circumstances, it has been proposed to detect the TDC position directly by using microwaves. According to this method, a microwave antenna is disposed within a combustion chamber of an engine, which acts as a microwave resonance cavity.
In this case, the TDC position can be detected by measuring the amplitude of the reflected microwaves varying with the reciprocation of the piston.
This microwave type detector is superior in that the TDC position can be accurately detected, but has a problem that the cost thereof is high.